Battery pack retention assembly and retention method

ABSTRACT

An exemplary method of securing portions of a battery pack includes, among other things, slidably engaging a portion of a battery cell frame within a channel of an extrusion, and securing the extrusion to a support to secure the battery cell frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/534,430, which was filed on 6 Nov. 2014 and is incorporated herein byreference.

TECHNICAL FIELD

This disclosure is directed toward retaining areas of a battery packand, more particularly, to utilizing an extrusion to secure portions ofa battery array within a battery pack.

BACKGROUND

Generally, electrified vehicles differ from conventional motor vehiclesbecause electrified vehicles are selectively driven using one or morebattery-powered electric machines. Conventional motor vehicles, bycontrast, rely exclusively on an internal combustion engine to drive thevehicle. Electrified vehicles may use electric machines instead of, orin addition to, the internal combustion engine.

Example electrified vehicles include hybrid electric vehicles (HEVs),plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, andbattery electric vehicles (BEVs). A powertrain of an electrified vehicleis typically equipped with a battery pack having battery cells thatstore electric power for powering the electric machines.

The battery pack can include multiple arrays of battery cells containedwithin a housing. Securing the arrays can be required.

SUMMARY

A method of securing portions of a battery pack according to anexemplary aspect of the present disclosure includes, among other things,slidably engaging a portion of a battery cell frame within a channel ofan extrusion, and securing the extrusion to a support to secure thebattery cell frame.

In another example of the foregoing method, the battery cell frameextends about the perimeter of at least one battery cell.

In another example of any of the foregoing methods, the portion is afoot extending laterally outward from the remaining portions of thebattery support frame.

In another example of any of the foregoing methods, the extrusionengages a portion of a plurality of other battery cell frames.

In another example of any of the foregoing methods, the method furthercomprises using the extrusion to limit both upward and downward movementof the battery cell frame.

In another example of any of the foregoing methods, the method furthercomprises snap-fitting the extrusion to the battery cell frame.

A battery pack securing method according to another exemplary aspect ofthe present disclosure includes engaging a portion of a battery cellframe within a channel of an extrusion, the channel provided by upperand lower flanges extending from a wall, snap-fitting a snap-fit featureduring the engaging, the snap-fit feature disposed entirely within thechannel, securing the extrusion to a support to secure the battery cellframe.

In another example of the foregoing method, the snap-fit featureincludes ridge and groove that are positioned entirely within thechannel when the extrusion engages the portion such that ridge andgroove are both spaced a distance from a leading edge of the upperflange and a leading edge of the lower flange.

In another example of any of the foregoing methods, the upper and lowerflanges extend from the wall to the respective leading edges.

Another example of any of the foregoing methods includes slideablyreceiving the portion within the channel during the engaging.

In another example of any of the foregoing methods, the extrusionextends longitudinally along a first axis, and the snap-fit featurecomprises a channel and a groove extending along a second axis alignedwith the first axis.

Another example of any of the foregoing methods includes securing an endcap to a longitudinal end portion of the extrusion to limit movement ofthe extrusion relative to the portion along the first axis.

In another example of any of the foregoing methods, the extrusion has a“C” shaped cross-sectional profile.

In another example of any of the foregoing methods, the channel isprovided entirely by the upper flange, the lower flange, and the wall asa monolithic structure.

The embodiments, examples and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

DESCRIPTION OF THE FIGURES

The various features and advantages of the disclosed examples willbecome apparent to those skilled in the art from the detaileddescription. The figures that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a schematic view of an example powertrain of an electrifiedvehicle.

FIG. 2 is a schematic perspective view of a battery array withinpowertrain of FIG. 1.

FIG. 3 is a schematic section view of a battery pack of the powertrainof FIG. 1 incorporating the battery array of FIG. 2.

FIG. 4 is a close-up perspective view of example support structures thathold battery cells within the array of FIG. 2.

FIG. 5 is a perspective view of an example extrusion that secures thebattery array of FIG. 2 within the battery pack of FIG. 3.

FIG. 6 shows a close-up perspective view of the extrusion of FIG. 5securing the battery array of FIG. 2 within the battery pack of FIG. 3.

FIG. 7 shows a perspective view of selected portion of the battery packof FIG. 3.

FIG. 8 shows a side view of the extrusion of FIG. 4 disengaged from thebattery array of FIG. 2.

FIG. 9 shows a side view of the extrusion of FIG. 4 engaged with thebattery array of FIG. 2.

FIG. 10 shows a perspective view of the extrusion of FIG. 4 engaging thearray in a first position.

FIG. 11 shows the extrusion of FIG. 4 engaging the array in a secondposition.

DETAILED DESCRIPTION

This disclosure relates generally to an extrusion that secure a batteryarray within a battery pack. The extrusion provides effective retentionwithin a relatively tight packaging space.

FIG. 1 schematically illustrates a powertrain 10 for a hybrid electricvehicle (HEV). The powertrain 10 includes a battery pack 14, a motor 18,a generator 20, and an internal combustion engine 22.

The motor 18 and generator 20 are types of electric machines. The motor18 and generator 20 may be separate or may have the form of a combinedmotor-generator.

In this embodiment, the powertrain 10 is a power-split powertrain systemthat employs a first drive system and a second drive system. The firstand second drive systems generate torque to drive one or more sets ofvehicle drive wheels 26 of the electrified vehicle. The first drivesystem includes a combination of the engine 22 and the generator 20. Thesecond drive system includes at least the motor 18, the generator 20,and the battery pack 14. The motor 18 and the generator 20 are portionsof an electric drive system of the powertrain 10.

The engine 22, which is an internal combustion engine in this example,and the generator 20 may be connected through a power transfer unit 30,such as a planetary gear set. Of course, other types of power transferunits, including other gear sets and transmissions, may be used toconnect the engine 22 to the generator 20. In one non-limitingembodiment, the power transfer unit 30 is a planetary gear set thatincludes a ring gear 32, a sun gear 34, and a carrier assembly 36.

The generator 20 can be driven by engine 22 through the power transferunit 30 to convert kinetic energy to electrical energy. The generator 20can alternatively function as a motor to convert electrical energy intokinetic energy, thereby outputting torque to a shaft 38 connected to thepower transfer unit 30. Because the generator 20 is operativelyconnected to the engine 22, the speed of the engine 22 can be controlledby the generator 20.

The ring gear 32 of the power transfer unit 30 can be connected to ashaft 40, which is connected to vehicle drive wheels 26 through a secondpower transfer unit 44. The second power transfer unit 44 may include agear set having a plurality of gears 46. Other power transfer units mayalso be suitable. The gears 46 transfer torque from the engine 22 to adifferential 48 to ultimately provide traction to the vehicle drivewheels 26. The differential 48 may include a plurality of gears thatenable the transfer of torque to the vehicle drive wheels 26. In thisexample, the second power transfer unit 44 is mechanically coupled to anaxle 50 through the differential 48 to distribute torque to the vehicledrive wheels 26.

The motor 18 can also be employed to drive the vehicle drive wheels 26by outputting torque to a shaft 52 that is also connected to the secondpower transfer unit 44. In one embodiment, the motor 18 and thegenerator 20 cooperate as part of a regenerative braking system in whichboth the motor 18 and the generator 20 can be employed as motors tooutput torque. For example, the motor 18 and the generator 20 can eachoutput electrical power to the battery pack 14.

Referring now to FIGS. 2 to 4, the example battery pack 14 provides arelatively high-voltage battery that stores generated electrical powerand outputs electrical power to operate the motor 18, the generator 20,or both.

The battery pack 14 includes a plurality of arrays 60. Each of thearrays 60 includes a plurality of individual battery cells 64 heldwithin a support structure 68. For example, each of the arrays 60 mayinclude from thirty to fifty individual battery cells 64. The batterycells 64 are distributed along an axis A.

The support structure 68 includes, among other things, a battery cellframe 70 about the perimeter of each of the battery cells 64. Each frame70 supports two individual battery cells 64 in this example. The frames70 are a polymer material in this example.

The frames 70 and battery cells 64 are held axially between end walls72. The frames 70 and the battery cells 64 are held laterally betweenside walls 74.

The frames 70 are disposed on a cold plate 76. A coolant can circulatesthrough channels within the cold plate 76 to carry thermal energy fromthe arrays 60. Cooling fins (not shown) may be placed between axiallyadjacent battery cells 64 to communicate thermal energy downward to thecold plate 76.

The battery pack 14 includes a case 80 that houses the arrays 60. Thecase includes a lid 82 secured to a floor 84.

In this example, the battery pack 14 includes supports 86 extendinglongitudinally in a direction aligned with the axis A. The supports 86are positioned between arrays 60 within the battery pack 14. Thesupports 86 have a “U” shaped profile such that an open area 90 can beprovided between the supports 86 and the floor 84 when the supports 86are secured to the floor 84. The supports 86 can be welded to the floor84 of the case 80, for example.

The frames 70 include feet 94 extending laterally outward from the axisA. The feet 94 may extend laterally outside the cold plate 70.

To secure the array relative to the case 80, an extrusion 100 engagesthe feet 94 on one lateral side of the array 60. The extrusion 100 isthen secured to the support 86 to stabilize the array 60 within thebattery pack 14. The example arrays 60 are secured, through theextrusion 100 and ridge member 86, to the floor 84 of the case 80.

Referring now to FIGS. 5 to 11 with continuing reference to FIGS. 2 and3, the example extrusion 100 includes an upper retention flange 104, alower retention flange 108, a wall 112, and a securement flange 116. Theupper retention flange 104 and the lower retention flange 108 extend ina first direction from the opposing ends of the wall 112 to provide achannel 118. The securement flange 116 extends from the wall 112opposite the upper retention flange 104 and the lower retention flange108.

The shape of the channel 118 corresponds generally to the shape of thefeet 94. The example channel 118 has a “C” shaped cross-sectionalprofile.

When the feet 94 are received within the channel 118, the upperretention flange 104 is positioned against an upwardly facing surface120 of the feet 94, and the lower retention flange 108 is positionedagainst the downwardly facing surfaces 124 of the feet 94.

The feet 94 and the extrusion 100 include a snap-fit feature 128 to helphold the feet 94 within the channel 118 of the extrusion 100. Theexample snap-fit feature 128 includes a ridge 132 and a groove 136. Theridge 132 extends upwardly from the lower retention flange 108. Thegroove 136 is provided within the downwardly facing surface 124 of thefeet 94. When the feet 94 are positioned within the channel 118, theridge 132 contacts the sides of the groove 136 to prevent the extrusion100 from moving laterally outward relative to the feet 94.

The example extrusion 100 extends longitudinally from a first end 140 toan opposing second end 144 along an axis that is generally aligned withthe axis A of the array 60. The extrusion 100 is a metallic material,such as an aluminum.

During assembly, the lid 82 is detached from the floor 84 such that thearrays 60 can be positioned within the battery pack 14. In this example,the feet 94 are positioned within the extrusion 100 prior to positioningthe arrays 60 within the pack 14. Feet on the opposing lateral side ofthe arrays 60 are positioned within another extrusion. Notable, theextrusion 100 and the other extrusion have a common cross-sectionalprofile. The same extrusion manufacturing process can thus provideextrusions to engage feet on both sides of the arrays 60.

The extrusion 100 can slideably engage the feet 94 to position the feet94 within the extrusion. FIG. 10 shows the extrusion 100 in a partiallyslid position relative to the feet 94. FIG. 11 shows the extrusion 100in a fully slid position relative to the feet 94.

When the feet 94 are positioned within the extrusion 100, and theextrusion 100 is axially aligned with the feet 94 as is shown in FIG.11, the arrays 60 are then positioned on the floor 84 of the batterypack 18.

In some examples, after positioning the extrusion 100 on the feet 94 asshown in FIG. 11, end caps 158 are secured to the first end 140 and thesecond end 144 to prevent movement of the extrusion 100 relative to thefeet 94 along the axis as the array 60 is positioned upon the floor 84.The end caps 158 are welded to the extrusion 100, for example.

The securement flange 116 provides apertures 160 corresponding toapertures 164 provided within the supports 86. The arrays 60 and theextrusion 100 are positioned within the battery pack 18 such that theapertures 160 and 164 are aligned. A mechanical fastener 168 is thepositioned within the apertures 160 and 164 to hold the extrusion 100relative to the supports 86. A lock nut may be welded to the supports 86within the open area 90 provide a threaded connection to the fastener168.

When the extrusion 100 is secured to the supports 86, the extrusion 100limits vertical movements of the array 60. Vertical upward movement ofthe array 60 is limited by the upwardly facing surface 120 contactingthe upper retention flange 104. Movements of array 60 along the axis Aare limited by the end walls 72.

Features of the disclosed examples include a retention strategy forarrays within a battery pack. The retention strategy is cost-effectiveand provides retention within relatively tight packaging areas. Usingthe extrusion for retention may reduce labor time for installationcompared to other conventional fastening methods. The thicknesses of theextrusion can be adjusted at various axial positions if localstrengthening is required. Cost and time for developing a retentionfeature for the battery pack is also reduced.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this disclosure. Thus, the scope of legal protectiongiven to this disclosure can only be determined by studying thefollowing claims.

We claim:
 1. A method of securing portions of a battery pack,comprising: slidably engaging a portion of a battery cell frame within achannel of an extrusion; and securing the extrusion to a support tosecure the battery cell frame.
 2. The method of claim 1, wherein thebattery cell frame extends about the perimeter of at least one batterycell.
 3. The method of claim 1, wherein the portion is a foot extendinglaterally outward from the remaining portions of the battery supportframe.
 4. The method of claim 1, wherein the extrusion engages a portionof a plurality of other battery cell frames.
 5. The method of claim 1,further comprising using the extrusion to limit both upward and downwardmovement of the battery cell frame.
 6. The method of claim 1, furthercomprising snap-fitting the extrusion to the battery cell frame.
 7. Themethod of claim 1, wherein the channel is provided by an upper retentionflange, a lower retention flange, and a wall of the extrusion, the upperretention flange extending from the wall to an upper retention flangeleading edge, the lower retention flange extending from the wall to alower retention flange leading edge, and further comprising snap-fittinga ridge within a groove when the channel receives the portion, thesnap-fit feature position entirely within the channel when the channelreceives the portion such that the snap-fit feature is spaced a distancefrom both the upper retention flange leading edge and the lowerretention flange leading edge.
 8. The method of claim 7, wherein theextrusion extends longitudinally along a first axis, and the channel andthe groove extend along a second axis aligned with the first axis. 9.The method of claim 7, wherein the portion is a foot extending laterallyfrom other portions of the frame, the upper retention flange positionedagainst an upwardly facing surface of the foot when the channel receivesthe foot, the lower retention flange positioned against a downwardlyfacing surface of the foot when the channel receives the foot.
 10. Abattery pack securing method, comprising: engaging a portion of abattery cell frame within a channel of an extrusion, the channelprovided by upper and lower flanges extending from a wall; snap-fittinga snap-fit feature during the engaging, the snap-fit feature disposedentirely within the channel; and securing the extrusion to a support tosecure the battery cell frame.
 11. The battery pack securing method ofclaim 10, wherein the snap-fit feature includes ridge and groove thatare positioned entirely within the channel when the extrusion engagesthe portion such that ridge and groove are both spaced a distance from aleading edge of the upper flange and a leading edge of the lower flange.12. The battery pack securing method of claim 11, wherein the upper andlower flanges extend from the wall to the respective leading edges. 13.The battery pack securing method of claim 10, further comprisingslideably receiving the portion within the channel during the engaging.14. The battery pack securing method of claim 13, wherein the extrusionextends longitudinally along a first axis, and the snap-fit featurecomprises a channel and a groove extending along a second axis alignedwith the first axis.
 15. The battery pack securing method of claim 14,securing an end cap to a longitudinal end portion of the extrusion tolimit movement of the extrusion relative to the portion along the firstaxis.
 16. The battery pack securing method of claim 10, wherein theextrusion has a “C” shaped cross-sectional profile.
 17. The battery packsecuring method of claim 10, wherein the channel is provided entirely bythe upper flange, the lower flange, and the wall as a monolithicstructure.